function Ball (radius, color) {
	 if (radius === undefined) { radius = 40; }
	 if (color === undefined) { color = "#ff0000"; }
	 this.x = 0;
	 this.y = 0;
	 this.radius = radius;
	 this.vx = 0;
	 this.vy = 0;
	 this.rotation = 0;
	 this.scaleX = 1;
	 this.scaleY = 1;
	 this.color = utils.parseColor(color);
	 this.lineWidth = 1;
}
Ball.prototype.draw = function (context) {
	 context.save();
	 context.translate(this.x, this.y);
	 context.rotate(this.rotation);
	 context.scale(this.scaleX, this.scaleY);
	 context.lineWidth = this.lineWidth;
	 context.fillStyle = this.color;
	 context.beginPath();
	 //x, y, radius, start_angle, end_angle, anti-clockwise
	 context.arc(0, 0, this.radius, 0, (Math.PI * 2), true);
	 context.closePath();
	 context.fill();
	 if (this.lineWidth > 0) {
		context.stroke();
	 }
	 context.restore();
}; 
Ball.prototype.getBounds = function () {
 return {
 x: this.x - this.radius,
 y: this.y - this.radius,
 width: this.radius * 2,
 height: this.radius * 2
 };
};